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Abstract

Methods: This is a prospective cohort study of children ages 5 to 17 years in which we analyzed the prevalence of headache 3 and 12 months after mild TBI (mTBI; n = 402) and moderate/severe TBI (n = 60) compared with controls with arm injury (AI; n = 122).

Conclusions: Pediatric TBI is associated with headache. A substantial number of children suffer from headaches months after their head injury. The prevalence of headache during the year after injury is related to injury severity, time after injury, age, and gender. Girls and adolescents appear to be at highest risk of headache in the months after TBI.

What’s Known On This Subject:

Over 500 000 children in the United States sustain a traumatic brain injury (TBI) each year. Headaches are commonly reported after TBI in adults, but little is known about the epidemiology of headache after pediatric TBI.

What This Study Adds:

Headaches are more common 3 months after pediatric TBI than after arm injury. The frequency of headache after TBI is related to patient gender, age, and injury severity. Headaches after mild TBI were most common among girls and teenagers.

Headache is one of the most common and troubling sequelae of traumatic brain injury (TBI) and concussion. In the adult population, 18% to 33% of those who suffer from TBI report headaches 1 year after the injury,1 and headache is reported more frequently after mild TBI (mTBI) than moderate/severe TBI.2 Over 500 000 children are evaluated in hospitals for TBI annually in the United States.3 However, there are few data on headache after TBI in children. Recent studies have revealed that 14% of school-aged children remained “symptomatic” 3 months after mTBI, and 2.3% of all children remained symptomatic 12 months after mTBI,4,5 but few studies have focused on headache. Most investigations of pediatric posttraumatic headache have been small, retrospective, lacked a control population, and/or involved only short-term follow-up.6–8 In children, chronic headaches interfere with school, social function, parental productivity, and are associated with poor quality of life.9 Disability due to posttraumatic headache is likely to be of greater importance as children with TBI may concomitantly suffer from cognitive deficits and other neurobehavioral symptoms related directly to the initial brain injury.10,11

The Child Health After Injury Study is a large prospective cohort study designed to evaluate outcome and health after pediatric TBI compared with a control population of children with arm injury (AI).12 Our goal was to use data from this study to determine the prevalence of headache at 3 and 12 months after mild, moderate, and severe TBI compared with a control population with AI to determine if TBI is associated with headache 3 and 12 months after injury. In addition to determining the prevalence of headache after pediatric TBI, we examined age- and gender-related differences in headache frequency after TBI because both TBI and headache syndromes have age- and gender-dependent features. Age may be associated with recovery after mTBI,13 girls report concussion more often than boys,14 and outcome after TBI may be different for male and female subjects.15–18 In addition, posttraumatic headaches often share many characteristics with migraine headaches.19 The risk of migraine is similar in young boys and girls, but in puberty this ratio begins to change and the risk of migraine for girls, but not boys, increases with age until it reaches adult levels in late adolescence.20 Thus, we felt that the frequency of headache after TBI was likely to be associated with the age and gender of the affected child and these relationships have not been well characterized in previous studies.

Methods

Patient Population

All study procedures were approved by the human subject committees of the participating institutions. As described in previous reports,12 in the Child Health After Injury Study we identified all children under the age of 18 years treated for a TBI or an upper extremity fracture either in the emergency department or as an inpatient in a study hospital. There were 9 participating institutions in King County, WA (1 children’s hospital, 2 university operated hospitals, and 6 community hospitals) and 1 in Philadelphia, PA (1 children’s hospital, from which only inpatient TBI cases were chosen). Study participants were the parents of children randomly selected from the list of all eligible children treated between March 1, 2007, and September 30, 2008, and contacted in-person or by letter and follow-up telephone call. In addition to parental involvement, adolescent subjects 14 years or older at the time of follow-up also completed separate surveys.

In the primary analysis of headache at 3 and 12 months after injury, we excluded those children younger than 5 years old at the time of injury who may not be able to reliably and specifically identify headache as a significant complaint due to immature communicative and cognitive skills.

Definition of TBI and Severity of TBI

We used the definition of TBI described in the 2002 Centers for Disease Control and Prevention (CDC) report21: an injury (blunt or penetrating) to the head that was documented in the medical record, with 1 of the following conditions attributed to brain injury: observed or reported decreased level of consciousness, amnesia, or objective neurologic or neuropsychological abnormality or diagnosed with intracranial lesion. We used the CDC Mild TBI Work Group Report22 and the World Health Organization Collaborating Center Task Force on Mild Traumatic Brain Injury23 to define mTBI. Moderate TBI was defined by the best motor Glasgow Coma Scale (GCS) of 4 or 5 24 hours after injury or a score of 6 for those who do not meet the criteria for mTBI, following the methods used in our previous work.24 Severe TBI was defined as best motor GCS of 1 to 3 at 24 hours after injury. Because there were relatively few patients in the latter 2 groups, they were combined for this analysis.

Definition of Control Patients

We used patients with arm fractures who were treated in the same King County study hospitals as those with TBI as controls. This is consistent with the CDC recommendations of choice of controls and with our own previous studies on TBI.24–26

Procedures

For those who agreed to participate, a baseline interview was administered as soon as possible after injury to 1 parent or guardian. Follow-up interviews were conducted 3 and 12 months after the date of the index injury with parents and with adolescents 14 and older who were able to complete the survey, as previously described.12

Definition of Headache

Parents answered the same question about their child’s headache on the 3- and 12-month follow-up surveys. The parent was asked to “rate any headache pain by indicating the child’s headache on average in the last week” by using a 0 to 10 scale where “0 is no pain and 10 is pain as bad as you can imagine.”

In addition, each adolescent aged 14 years and older was interviewed, if cognitively able, at 3 and 12 months after injury and asked 3 questions about headache:

“In the past 4 weeks, how much have you been bothered by headaches?” The teenager was asked to choose from 3 options, “not bothered,” “bothered a little,” and “bothered a lot.”

“Please rate any headache pain by indicating the number that best describes your headache on average in the past week” by using a 0 to 10 scale.

Using the Wong-Baker FACES pain rating scale27 with 6 faces labeled A to F indicating increasing degree of pain, the teenager was asked to choose “which face shows how much your head hurt in the past week?”

In our primary analysis, we defined “headache” as pain rated ≥1 of 10, and “serious headache” as pain rated ≥5 of 10 on the parental survey to have consistent definitions for the entire cohort. We also examined the responses on the teenager survey where “serious teen headache” was defined as “bothered a lot” by headache, ≥5 of 10 score on 0 to 10 scale, or report of headache of C, D, E, or F on the faces scale.

Data Analysis

We compared the demographic and clinical characteristic of children with AI, mTBI, or moderate/severe TBI by using χ2 and 1-way analysis of variance for categorical and continuous variables, respectively, to assess for significant differences. Given the high frequency of headache, we used Poisson regression to estimate relative risk (RR) of headache after mTBI and after moderate/severe TBI compared with controls, controlling for age, gender, child race, insurance status, and parental education level. For the parent survey, we assessed the differences of any or serious headache at 3 and 12 months after injury for mild or moderate/severe TBI versus controls in: a) all patients, b) stratified by age (> or ≤12 years) controlling for gender and factors listed above, and c) stratified by gender controlling for age and factors listed above. We also compared the prevalence of serious headache at 3 months after injury for different age groups (age 5–7, 8–10, 11–13, and 14–17 years) among boys and girls to examine trends in headache prevalence associated with age. For the teen survey, we assessed serious teen headache at 3 and 12 months after injury in all patients and stratified by gender controlling for insurance status.

Results

There were a total of 1627 eligible patients with TBI and 1905 with AI between 5 and 17 years of age at the time of injury. We randomly selected, with probability of selection varying by age, gender, and hospital admission strata, 1507 potential patients with TBI and 495 AI controls (92.6% and 26.0% of those treated, respectively) for potential entry into the study. Of these, 483 patients with TBI and 221 controls were unable to be contacted, 196 and 35 were ineligible, and 316 and 103 refused. Thus, 512 patients with TBI (61.8% of contacted patients determined to be eligible) and 137 with AIs (55.0% of contacted patients determined to be eligible) were enrolled in the study; all completed the baseline interview. Follow-up interviews were completed for 97.3% of patients with TBI and 95.6% of control patients at 3 months and 92.6% and 91.2%, respectively, at 12 months. Comparing enrollees to those selected but not enrolled, we found that enrollees were somewhat older (12.1 years [SD 3.9] vs 11.7 years [SD 4.0], P < .02), of similar gender (70.4% boys versus 69.0%, P = .54), and more likely to have a moderate/severe TBI (11.6% vs 1.6%).

For children enrolled in the study, children with TBI were slightly older than controls. Compared with patients with mTBI or AI, patients with moderate/severe TBI were more likely to be nonwhite, lack private health insurance, have lower income households, and have less educated parents, reflecting the population at the Philadelphia site (Table 1).

Injury Characteristics

The majority of mTBIs were sustained in a fall or when the head struck an object. Most moderate/severe TBIs were the result of a motor vehicle or bicycle crash or fall; 76% of AIs were the result of a fall. The lowest motor GCS in the emergency department was normal (6/6) for 95% of those with mTBI and 99% of those with AI. However, 85% of those with moderate/severe TBI had lowest motor GCS <6. All children with moderate/severe TBI, 35% of those with mTBI, and 17% of those with AI were admitted to the hospital.

Headache 3 Months After Injury

Three months after injury, headache was reported by parents for 43% of children with mTBI, 37% of children with moderate/severe TBI, and 26% of controls. Given the strong association of primary headache disorders with gender and age, we performed a stratified analysis as well as multivariate analysis (Table 2 and Fig 1). Mild TBI was associated with an increased risk of headache at 3 months compared with controls after adjusting for age, gender, race, insurance, and parental education (RR: 1.7 [95% confidence interval (CI): 1.2–2.3]). In stratified analysis girls, but not boys, had a significantly higher risk of any headache 3 months after mTBI compared with controls (RR: 2.4 [95% CI: 1.4–4.2]). The frequency of headache 3 months after mTBI appeared to be elevated in both younger and older children but was significant only for adolescents (RR: 1.8 [95% CI: 1.1–3.1]; Table 2). The prevalence of headache 3 months after moderate/severe TBI was significantly higher only for young children (RR: 2.0 [95% CI: 1.2–3.4]) and not overall or in teenagers.

We found similar trends for prevalence of serious headache at 3 months after TBI. The frequency of serious headache appeared to be increased after mTBI overall and in teenagers but was only significantly higher for girls with mTBI (29% vs 10%; RR: 2.6 [95% CI: 1.0–6.6]). In addition, for girls, the prevalence of serious headache 3 months after mTBI increased with age: 7% aged 5 to 7 years, 20% aged 8 to 10 years, 29% aged 11 to 13 years, and 45% aged 14 to 17 years. This trend was not seen in boys with mTBI or controls of either gender (Figs 2 and 3). The prevalence of serious headache after moderate/severe TBI was significantly greater only for younger children (32% vs 8%; RR: 3.5 [95% CI: 1.2–10.0]; Table 2).

The findings of the adolescents’ self-report were similar to the parental report of headaches at 3 months. While statistical significance was not achieved for most questions, there appeared to be an association between complaints of headache and mTBI for teen-aged girls on the different measures of teen headache. Three months after injury, 55% of teen-aged girls with mTBI reported serious headache compared with 23% of controls (RR: 2.5 [95% CI: 1.0–6.5]). Thirty-two percent of teen-aged girls with mTBI reported being bothered a lot by headache and 52% rated their headache as greater than or equal to grade C on the Faces scale compared with 8% and 30% of controls, respectively. There was no significant association between mTBI and headache for adolescent boys or for teenagers of either gender after moderate/severe TBI 3 months after injury (Table 3).

Headache 12 Months After Injury

Twelve months after injury, headache was reported by parents for 41% of children with mTBI and 34% with moderate/severe TBI and 34% with AI (not significant; Table 4). However, in the stratified analyses, girls with mTBI appeared to have a higher prevalence of headache 12 months after injury than controls, although the difference was not statistically significant (52% vs 36%; RR: 1.3 [95% CI: 0.85–2.0]). In contrast to the 3-month follow-up, younger children with moderate/severe TBI did not appear to have an increased frequency of headache 12 months after injury compared with controls (Table 4).

There was no significant difference in prevalence of serious headache at 12 months after injury for children with mTBI or moderate/severe TBI compared with controls. However, girls with mTBI appeared to have a higher prevalence of serious headache than controls 12 months after injury (27% vs 10%; RR: 2.2 [95% CI: 0.9–5.6]; Table 4). In addition, adolescent girls reported more headaches 12 months after mTBI than controls for all headache questions on the teenager survey. Although the differences were substantial, they did not reach statistical significance in the multivariate analysis (bothered a lot by headache: 26% vs 7%; Faces Scale grades C to F: 64% vs 11%; ≥5 of 10 headache pain rating: 44% vs 14%; Table 5). Similar trends were also seen for teen-aged girls with moderate/severe TBI as shown in Table 5. This teenaged subgroup analysis is limited by small sample size, with 12 girls with moderate/severe TBI and 14 controls.

Discussion

Headache is a common complaint after TBI, but there is little information regarding chronic headache after TBI in children. We found that headache was more common after mTBI than AI in children 3 months after injury; this excess frequency was particularly notable in adolescents and girls. Moderate/severe TBI was associated with headache frequency at 3 months for young children but not for teenagers. At 12 months after injury, girls with mTBI or moderate/severe TBI had a higher rate of headache compared with controls, but this did not reach statistical significance in this sample. We also found a weak association between moderate/severe TBI and headache at 12, but not 3, months after injury for adolescent girls. These findings are in accordance with recent studies revealing that postconcussive symptoms were more common after mTBI than extracranial injury in children4,5 and that women have a higher risk of headache after mTBI than men.17

The association between age and gender and frequency of headache after TBI in children is particularly intriguing. The authors of previous studies suggest that girls are more likely to report significant postconcussive symptoms after mTBI than boys.15,28 One study revealed a higher risk of new headache 3 months after concussion for women but not for men, girls, or boys although they grouped “minors” together without differentiating between children and adolescents.17 In addition, some authors have suggested that migraine may be a risk factor for posttraumatic headaches,29 and posttraumatic headaches often have migrainous characteristics.19,30 The prevalence of migraine is associated with age and gender and is roughly equivalent in boys and girls until puberty when migraine prevalence begins to increase with age in girls, but not boys, reaching adult levels in late adolescence when migraine is much more common in girls than boys.20,31 We found a similar pattern of headache after mTBI. Adolescent girls, but not boys, with mTBI had higher rates of headache after injury compared with controls, and there was a trend for increasing rates of headache associated with increasing age for girls with mTBI, but not boys, mirroring the pattern seen in migraine. These findings lend support to the theory that the pathophysiology of posttraumatic headaches after mTBI may share similarities with the pathophysiology of migraine.29

Interestingly, 3 months after moderate/severe TBI, teen-aged girls did not report more headaches than controls, but at 12 months, 42% of teen-aged girls with moderate/severe TBI were bothered a lot by headaches compared with 7% of controls. However, this subanalysis was limited by small sample size and bears further study with larger groups.

Adult studies of headache after TBI have revealed that chronic headache is more common after mTBI than moderate/severe TBI.2 Although there are differences in the pathophysiology of brain injury after mild and moderate/severe head trauma, the reason for the differences in headache risk after different types of TBI in adults remains unclear.2 In our study, we found that the prevalence and risk for headache after moderate/severe TBI followed the adult pattern for adolescents but not for younger children. Given that the headaches were reported by parents, this finding in younger children may reflect parental concern or expectations for these young children with significant brain injury. However, these findings may support the theory that the developing brain responds to TBI differently than the adult brain, in which case one would expect to find differences in the response to and recovery from different types of brain injury between children, adolescents, and adults.

Although this study is one of the only large, prospective and controlled studies of headache after mild and moderate/severe pediatric TBI, there are several limitations. One issue is the lack of data on preinjury headache. If children with TBI had a higher rate of preinjury headache than those with AI, the results would be biased in favor of finding an association between TBI and headache. However, at 3 months after injury the difference between rates of serious headache after mTBI and AI (6.7%) is similar to the rate of new headaches after mTBI reported by Barlow et al (7.9%).5 It is also possible that the parents of children with TBI were more likely to report headaches and/or rate them as more severe than the control parents. This could be due to concern about head pain after a brain injury, anxiety about the injury, or due to cultural expectation of headaches after head injury. However, we could also be missing information about less frequent, but significant headaches as parents reported only on headaches present in the 7 days before the survey. We also had limited information regarding headache characteristics. Therefore, we were unable to classify the headaches as migraine, tension, or “other” headache. We report prevalence of headache rather than “posttraumatic headache” because we have insufficient information about the headaches to accurately label them as posttraumatic according to the International Classification of Headache Disorders II criteria.32

Conclusions

Although many children do not report headaches after TBI, a substantial number suffer from headaches long after the initial brain injury. The association between TBI and headache is most remarkable in girls and adolescents after mTBI and in younger children after moderate/severe TBI. There may also be an association between both mild and moderate/severe TBI and headache 1 year after injury for adolescent girls. Thus, the epidemiology of headache after pediatric TBI may share similarities with the epidemiology of primary headache disorders such as migraine.

This study provides evidence that the response to and recovery from TBI is different in children, adolescents, and adults, and there are likely to be differences in symptoms of and recovery from TBI between boys and girls. Although only a fraction of children and adolescents with TBI develop chronic headaches related to their injury, because thousands of children sustain TBI each year, our findings indicate that many children and adolescents suffer from TBI associated headaches each year. We need to improve our understanding of pediatric TBI and recovery to develop effective treatment strategies for children of all ages.

National Center for Injury Prevention and Control. Report to Congress on Mild Traumatic Brain Injury in the United States: Steps to Prevent a Serious Public Health Problem. Atlanta, GA: Center for Disease Control and Prevention; 2003